From 5d86238b8cc3c6dba95e90eed9fb444bb276f02e Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Tue, 22 Aug 2023 17:44:01 +0200
Subject: Added initial implementation of scale mode

---
 src/scale.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 src/scale.c

(limited to 'src/scale.c')

diff --git a/src/scale.c b/src/scale.c
new file mode 100644
index 0000000..51d46fe
--- /dev/null
+++ b/src/scale.c
@@ -0,0 +1,102 @@
+typedef enum Scales {
+    SCALE_CHRM,
+    SCALE_MAJR,
+    SCALE_MINR,
+    SCALE_PMAJ,
+    SCALE_PMIN,
+    SCALE_BLUE,
+    SCALE_DORI,
+    SCALE_PHYR,
+    SCALE_LYDI,
+    SCALE_MIXO,
+    SCALE_LOCR,
+    SCALE_PERS,
+    SCALE_HMIN,
+    SCALE_IWAT,
+    SCALE_INSN,
+    SCALE_HIRA,
+    SCALE_NUM,
+} Scales;
+
+char *scale_short[] = {
+    "CHRM",
+    "MAJR",
+    "MINR",
+    "PMAJ",
+    "PMIN",
+    "BLUE",
+    "DORI",
+    "PHYR",
+    "LYDI",
+    "MIXO",
+    "LOCR",
+    "PERS",
+    "HMIN",
+    "IWAT",
+    "INSN",
+    "HIRA",
+};
+
+char *scale_long[] = {
+    "CHROMATIC",
+    "MAJOR",
+    "MINOR",
+    "PENTATONIC MAJOR",
+    "PENTATONIC MINOR",
+    "BLUES",
+    "DORIAN",
+    "PHYRGIAN",
+    "LYDIAN",
+    "MIXOLYDIAN",
+    "LOCRIAN",
+    "PERSIAN",
+    "HUNGARIAN MINOR",
+    "IWATO",
+    "IN-SEN",
+    "HIRAJOSHI",
+};
+
+typedef u8 Scale[12];
+Scale scales[] = {
+//   1  b2 2  b3 3  4 b5  5 b6  6 b7  7   <- Major
+    {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, // CHRM
+    {1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1}, // MAJR
+    {1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0}, // MINR
+    {1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0}, // PMAJ
+    {1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0}, // PMIN
+    {1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 1, 0}, // BLUE
+    {1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0}, // DORI
+    {1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0}, // PHYR
+    {1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1}, // LYDI
+    {1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0}, // MIXO
+    {1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0}, // LOCR
+    {1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1}, // PERS
+    {1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1}, // HMIN
+    {1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0}, // IWAT
+    {1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0}, // INSN
+    {1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0}, // HIRA
+};
+
+int current_scale = SCALE_CHRM;
+int current_scale_root = 0;
+
+s32
+scale_note(s32 current, s32 inc) {
+    if (inc > 1 || inc < -1) {
+        return CLAMP(current + inc, (s32)NOTE_C_2, (s32)NOTE_C_8 - 1);
+    }
+    s32 pos = current % 12;
+    s32 offset = 0;
+    for (int i = 1; i <= 12; i++) {
+        s32 k = (current_scale_root + pos + i * inc) % 12;
+        if (k < 0) {
+            k *= -1;
+            k = 12 - k;
+        }
+        offset += inc;
+        if (scales[current_scale][k] == 1) {
+            break;
+        }
+    }
+    return CLAMP(current + offset, (s32)NOTE_C_2, (s32)NOTE_C_8 - 1);
+}
-- 
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